Gas tube protector circuit



INVENTOR.

IRVING SAGER flhbrnsy l SAGER GAS TUBE PROTECTOR CIRCUIT Original Filed July 6, 1944 0.0. SOURCE June 16, 1953 Patented June 16, 1953 UNITED STATE s PATENT oFFrcEf' 1 Irving Sager, New York, N. Y.-, a'ssignor to the United States of America as represented by the Secretary of War Original application July c, 194 Serial Np. 543,741. Divided and this application October 31,1950, Serial No. 193,240

9 Claims. (01. 315-165) (Granted under Title 35, U. s. Code (1952),

sec. 266) 1 The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This application is a division of my application carrying any current-immediatelyupon theestablishment of the main cathode-anode circuit.

for patent on improvements in Line Pulse Modu- I lator, Serial Number 543,741, filed July 6,19%.

The present invention relates to a gas tube protector circuit and more particularly but not exclusively to such a circuit adapted to protect the igniting element of a gas tube circuit, particularly of 7 keys a pulse transmitter such as used in pulseeoho radio object locating systems. i

In such radio object locating systems, the transmitted exploratory pulses are of extremely short duration and high power, the effective operation of the system depending to averylarge extent on the power of the transmitted exploratory pulse. This type of operation requires very large concentrations of power during extremely short periods of time, and the task of delivering this power to the transmitter, as a rule, evolves upon the keyer, since plate modulation is assuming a more and more dominant position in the transmitter circuits of radio object locating systems.

is made of simple pulse generator circuits which include one or more mercury pool type tubes, generally known as ignitrons. A D. C. source is used for periodically charging an artificial line which, upon the line being fully charged, is discharged very quickly through one or more low impedance ignitrons.

Actual operation of ignitrons in keying circuits has disclosed the fact that the most sensitive element in the entire circuit is the ignitor electrode used for establishing the hot spot in the mercury pool of the ignitron. As is well known in the art, radio object locators as a rule operate continuously over long periods of time, this type of operation being especially common in connection with radio locators assigned for continuous routine surveillance of assigned areas. Since the establishment of ignition must take place in an I the ignitron type, that periodioally In the parent application referred to above, use 1 extremely short period of time and a very powerful pulse must be delivered to the ignitor electrode, the cumulative effect of this type of op-- eration eventually results in the premature burning out of the ignitor electrode. It has also been discovered that the life of the ignitor electrode and, as a consequence, of the entire keyen'may be increased many fold if positive precautions are taken to prevent the igfiitor electrode from I the sourceofpotential 30, resistors 20' and 22 com;

It is therefore the main object of my invention toprovide anignition circuit for an arcedischar'ge tube, wherein the discharge control electrode, is

protectedirom any possibleexposure to excessive current, thus prolonging the operating life of the tube and enabling it to be operated continuously for long periods of time. More specifically, the object or my invention is to provide a circuit which accomplishes the result of prolonging the life' of anignitronby means of a circuit for preventing the continuance of any current in the ignitor circuit immediately upon the establishment of full ionization inthe, ignitron;

Other objects will become apparent in the ensuing description.

The sole figure of the drawin is a schematic diagram of a keying circuit using only one igniany injuriousexcessive currents.

tron, the ignitor element being protected from A serie resonant circuit consisting of a source i of D.- C. potential 2, an inductance 6, a Guillemin artificial lined, and the primary winding 58 of a pulse transformer Bl), is used for periodically charging the Guilleminline. Due to the series.

resonance of the charging circuit, a. maximum voltage of twice that of source 2 is attained. The Guillernin line is then discharged throughan ar discharge tube suc as an ignitron a, delivering the necessarykeying' pulse to the primary Winding 58 of the transformer 60 and thence to a pulse transmitter L; A

Full ionization of ignitr'n 8, which then di charges the line 4, is' accomplishedby anjmpur circuit in the following manner: positive rctang'ular pulses IZare impressed on the control grid M of a tetro'de I6 through 'apulse transformer 26, said'ftetrode being normally biased so asto benon-conductive bymea'ns of fa voltage dividerconsisting or 1'esistors1l8,j20 and 22 corinected across a source of l l -C. potential 30. The control grid i l of the tetrodeflli isconnected to th'e'cathode 62 of the 'te'trode' through secondary winding} of transformer 26, and biasing resistor" l8 The'anode '32 of tetrodeilti is' con: nected to the primary winding 34' of a pulse trans; former Zdand thence to the positive terminal of pleting th ecathodfanode circuit. he remain gular pulse]? is thus amplifiedin redone It and impressed on the ,windihgMpf pulse; I

transformer 28 the.secondarywinding 36. ofthis transformer being connected on" one u 7 as 'ignitor electrode 38 of ignitron 8, and on the other side to the mercury pool cathode 40 of the ignitron. The cathode 40 is grounded through a small inductance coil 42. The rectangular pulse impressed on the ignitor electrode 38 establishes an are between the mercury pool and the ignitor 38, which at once produces full ionization of the ignitron, and the Guillemin line 4 discharges to ground.

The grid-cathode circuit of tetrode I6 is shunted by a normally nonconductive gas-filled control tube 44, the anode 46 of this tube being connected to the grid l4 of tetrode l6, whilethe cathode 48 of tube '44 is connected to a conductor 50 joining resistor I8 to secondary windin 24 of transformer 26. The grid 52 of the gas-filled tube 44 is connected to the same conductor 50 through a grid resistor 54, and through a coupling apparent that while I have shown and described my invention in its preferred form, many changes and modifications may be made without departing from the spirit of my invention as sought to be defined in the following claims.

I claim:

-1; A circuit comprising in combination: at least one arc-discharge tube having a cathode, an anode coupled to a potential that is positive relative tosaid cathode, and a discharge control electrode; an input circuit for impressing triggering pulses between said disabling electrode and said cathode; and control means responsive to the conduction of said tube, for disabling said input circuitonly until the cessation of each inr put pulse.

condenser 54 and a conductor 56 to the cathode 7 terminal 40 of the ignitron 8. It is this gas-filled. tube, connected across the input circuit of tetrode l6 and having its grid 52 coupled to the ignitron 8 through the condenser 54, that is used to prevent the continuance of current in the ignitor electrode upon ionization of the ignitron.

If the ignition of ignitron 8 actually took place after the maximum duration of the igniting pulse, and if the pulse ceased immediately uponthe full ionization of the ignitron, the ignitor electrode would carry only the current absolutely necessary to produce fullionization of the ignitron. Frequently however, when the estab lishment of the are between the mercury pool and the ignitor takes place some time before the cessation of the ignitionpulse, a relatively large voltage is still impressed on the ignitor electrode-cathode circuit even after the establishment of the necessary are and, as a consequence, the ignitor electrode will carry very large parasitic currents which are many times larger than the normal ignition currents. These parasitic currents cause premature burning out of the ignitor electrodes and the failure of keying circuits. The feed-back circuit, consisting of conductor 55 and condenser 54, and the gas-filled tube 44, are used to arrest any continued supply ofvoltage to the ignitor electrode circuit immediately upon the full ionization of the ignitron.

When a large cathode-anode current appears in the ignitron, the inductance coil 42 impresses a highv positive potential upon condenser 54 which produces immediate ionization of the gas-filled tube 44. Since this tube 44 is connected directly across the secondary winding 24 of transformer 26, the remaining portion of the rectangular pulse I2 is shorted by the low impedance of the gas-filled tube, and the control grid [4 of tetrode It becomes once more connected to the negative terminal of D.-C. source of potential, 30. Ac-' cordingly, tetrode It is at once disabled, and the voltage impressed on the ignitor circuit is removed immediately upon the closing of the main cathode-anode circuit in ignitron 8.

The circuit disclosed above offers a high degree of protection to the ignitor electrode and results in prolonging the life of this element which otherwise is the weakest point in keying systems. This circuit is of course equally useful with keying circuits using more than one ignitron, as shown in parent application referred to above, or when used to protect the control electrode of one or more gas thyratrons in a keyer.

It is believed that the construction and operation of my new protector circuit, as well as the many advantages thereof, will be apparent from the foregoing description. It will, therefore, be

potential having a negative, grounded terminal;

a cathode coupled through an inductance to ground, and a. discharge control electrode; a

;pulse transformer having a secondary winding connected between said control electrode and said cathode; a normally non-conductive vacuum. tube amplifier having at least one control grid receptive of a series of input pulsesto render said vacuum tube conductive, an anode connected to one end of the primary winding of said transformer, and a cathode coupled to the other end of said primary winding; and disabling means responsive to the conduction of said arc-discharge tube, for short-circuiting the input to said vacuum tube amplifier only until the cessation of each input pulse.

5. The circuit of claim 4, wherein said disabling 'means includes a normally non-conductive gasfilled tube coupled across the input to said vacuum tube amplifier and adapted to be rendered conductive upon the conduction of said arc-discharge tube.

6. The circuit of claim 5, wherein said disabling means further includes coupling means connecting the control electrode of said gas-filled tube and the cathode of said arc-discharge tube, said gas-filled tube having a grounded cathode.

7. The circuit of claim 6, wherein said aredischarge tube is an ignitron.

8. The circuit of claim 7, further including an artificial line adapted to be charged by said source of potential, said line being connected in Shunt with said ignitron and being discharged vby the triggering thereof, and a utilization circuit coupled to said line.

9. A circuit comprising in combination: at least one ignitron having an anode coupled to the positive terminal of a source of potential .having a negative, grounded terminal, a cathode coupled through an inductance to ground, and an ignitor electrode; a series resonant charging circuit including an artificial line connected in shunt with said ignitron for charging from said source of potential; a pulse transformer having a primary winding, and a secondary winding connected between said ignitor and said cathode of said ignitron; a normally non-conductive vacuum tube amplifier having at least one control: grid receptive ofa series ofinput pulses for rendering said amplifier conductive, an anode connected to one end of said primary winding and a cathode coupled to the other end of said primary winding; and a gas-filled tube having its anode connected to the control grid of said amplifier, its cathode connected to ground, and its discharge electrode coupled to the cathode of said ignitron, whereby, upon the firing of said ignitron, said artificial line will be discharged through said ignitron and will produce a potential across said inductance which will discharge said gas tube and short-circuit the input pulses applied to said amplifier, thereby preventing said ignitor from drawing current during the application of said pulses thereto and after said ignitron has been fired.

IRVING SAGER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 10 2,231,582 Knight Feb. 11, 1941 2,491,413 Lexa Dec. 13, 1949 2,503,735 Hess Apr. 11, 1950 

